Electrolyte and process for electro-depositing copper

ABSTRACT

IN ACCORDANCE WITH CERTAIN OF ITS ASPECTS, THIS INVENTION RELATES TO NOVEL COMPOSITION AND TO A PROCESS FOR ELECTRODEPOSITING BRIGHT, STRONGLY LEVELED, DUCTILE COPPER FROM AN AQUEOUS ACIDIC COPPER PLATING BATH CONTAINING CHLORIDE ION AND AT LEAST ONE MEMBER INDEPENDENTLY SELECTED FROM EACH OF THE FOLLOWING GROUPS: (A) A POLYSULFIDE COMPOUND OF THE FORMULA   R&#39;&#39;-(S)N-R-SO3M;   (B) A HETEROCYCLIC SULFUR COMPOUND CONTAINING THE GROUPING   -N(=O)Z=C(-S-R&#34;)-C(-)&lt;   WHERE R&#34;&#39;&#39; IS HYDROGEN, AN ALKYL GROUP OF 1-6 CARBON ATOMS, ARYL, ALKARYL OR ARALKYL GROUP.   -C(=N-R&#34;&#39;&#39;)-N(-R&#34;&#39;&#39;)2, -C(=N-R&#34;&#39;&#39;)-R&#34;&#39;&#39; OR -C(=S)-N(-R&#34;&#39;&#39;)2   AND/OR TAUTOMERS THEREOF, WHERE THE NITROGEN ATOM AND THE TWO CARBON ATOMS ARE PART OF A HETEROCYCLIC RING; AND (C) A POLYETHER CONTAINING AT LEAST 5 ETHER OXYGEN ATOMS PER MOLECULE; WHEREIN R IS INDEPENDENTLY A DIVALENT ALIPHATIC OR AROMATIC NON-HETEROCYCLIC GROUP OF 1-10 CARBON ATOM; R&#39;&#39; IS HYDROGEN, A METAL CATION, A MONOVALENT ALIPHATIC OR AROMATIC GROUP OF 1-20 CARBON ATOMS, OR THE GROUPS -R-SC3M OR -R-(S)Q-RSO3M WHEREIN Q IS AN INTEGER 2-5; M IS A CATION; Z IS 0 OR 1; R&#34; IS HYDROGEN, A METAL ION OR ONE OF THE GROUPS

United States Patent 3,804,729 ELECTROLYTE AND PROCESS FOR ELECTRO- DEPOSITING COPPER Otto Kardos, Ferndale, and Silvester P. Valayil, and Donald A. Arcilesi, Detroit, Mich., assignors to M & T Chemicals Inc., Greenwich, Conn. No Drawing. Filed June 19, 1972, Ser. No. 264,193

Int. Cl. C23h /20, 5/46 US. Cl. 204-52 R 46 Claims ABSTRACT OF THE DISCLOSURE In accordance with certain of its aspects, this invention relates to novel compositions and to a process for electrodepositing bright, strongly leveled, ductile copper from an aqueous acidic copper plating bath containing chloride ions and at least one member independently selected from each of the following groups:

(A) a polysulfide compound of the formula R'(S),,RS03M;

(B) a heterocyclic sulfur compound containing the grouping and/or tautomers thereof, where the nitrogen atom and the two carbon atoms are part of a heterocyclic ring; and

(C) a polyether containing at least 5 ether oxygen atoms per molecule;

wherein R is independently a divalent aliphatic or aromatic non-heterocyclic group of 1-l0 carbon atom; R is hydrogen, a metal cation, a monovalent aliphatic or aromatic group of 1-20 carbon atoms, or the groups -R--SC M or R(S) RSO M wherein q is an integer 2-5; M is a cation; Z is 0 or 1; R" is hydrogen, a metal ion or one of the groups where R is hydrogen, an alkyl group of 1-6 carbon atoms, aryl, alkaryl or aralkyl group.

This invention relates to novel processes and compositions for the electrodeposition of copper from aqueous acidic baths. More particularly, this invention relates to certain bath compositions containing specified combinations of chemical ingredients and to the use of such compositions to obtain bright, ductile, strongly leveled copper electrodeposits.

It is an object of this invention to obtain bright, ductile, leveled copper electrodeposits. A further object of the invention is to provide novel plating bath compositions from which bright copper electrodeposits may be obtained wherein said electrodeposits exhibit good leveling and ductility over wide current density ranges. Other objects of the invention will be apparent from the following detailed description.

In accordance with certain of its aspects, this invention relates to novel compositions and to a process for elec- 3,804,729 Patented Apr. 16, 1974 trodepositing bright, strongly leveled, ductile copper from an aqueous acidic copper plating bath containing chloride ions and at least one member from each of the following groups:

(A) a polysulfide compound of the formula R(S),,R-SO;M;

(B) a heterocyclic sulfur compound containing the grouping N=C(5- t g l 2 1k and/or tautomers thereof where the nitrogen atom and the two carbon atoms are part of a heterocyclic ring;

and

(C) a polyether containing at least 5 ether oxygen atoms per molecule;

where R'" is hydrogen, an alkyl group of 1-6 carbon atoms, aryl, alkaryl or aralkyl group.

The combination of these three additives in a chloridecontaining copper plating bath gives unexpected beneficial effects over the use of each additive alone in a chloridecontaining copper plating bath.

Simultaneous use of at least one member from each of the three groups of additives gives bright copper deposits over a wide current density range with strong leveling properties. As used herein,the term leveled denotes a surface which is smoother than its substrate. The high degree and rate of leveling leads to an important economy in finishing costs and materials. The improved low current density brightness (i.e. the widening of the bright current density range) is important it strongly profiled objects are to be plated. The polysnlfide sulfonates, as defined herein, have been found to be much more effective when employed according to the invention than the corresponding monosul'fides.

When used alone these classes of additives (denoted A, B, and C herein) may be found to be deficient in one or more aspects. Thus, the copper deposits obtained may not be bright, smooth, and may not exhibit adequate leveling properties over a sufficient current density range. Combinations utilizing two of the additives may give fairly bright copper deposits, but the current density range of brightness may be limited and/or the rate of leveling (decrease of surface roughness) may be low. Other double combinations of additives may give striated deposits and limited bright current density ranges.

The novel compositions of the invention may be employed in combination with aqueous acidic copper plating baths. Typical aqueous acidic copper plating baths which may be employed in combination with the novel additive compositions (A, B, and C) of the invention include the following:

20-80 mg./l.).

The basis metals which may be electroplated in accordance with the process of this invention may include ferrous metals, such as steel, iron, etc., bearing a surface layer of nickel or cyanide copper; zinc and its alloys including zinc-base die-cast articles bearing a surface layer of cyanide copper or pyrophosphate copper; nickel, including nickel alloys with other metals such as cobalt; aluminum, including its alloys, after suitable pretreatment, etc.

After the deposition of the bright leveled copper deposit of this invention, generally a bright nickel deposit and a chromium deposit (which may be microporous or microcracked) may be applied. The bright acid copper deposit of this invention contributes to the appearance and performance of the composite coating because of its very high rate of leveling, its excellent pore-filling capac ity, its high luster, good ductility and low internal stress. It improves corrosion resistance and permits economy in nickel use.

Because of its strong leveling properties, its very good performance at high current densities, and its very good mechanical properties (especially good ductility and low stress) the bright acid copper electrodeposits of this invention may be used for industrial applications such as electroforming, the plating of memory drums, printing rolls, etc. The process gives very good results also for the plating of non-conducting materials, such as plastics, after the usual pretreatment.

The plating conditions for electrodeposition from the aforementioned baths may, for example, include temperatures of C.-60 C. (preferably C.40 C.); pH (electrometric) of less than about 2.5; and a cathode current density of .1-50.0 amperes per square decimeter (asd).

Typical average current densities may be 2-20 asd for the sulfate bath and about 4-40 asd for the fluoborate bath. Air agitation, volume agitation, or mechanical agitation may increase the effective current density ranges and enhance the uniformity of the copper deposit.

In accordance with certain of its aspects, this invention relates to novel compositions and to a process for electrodepositing bright, strongly leveled, ductile copper from an aqueous acidic copper plating bath containing chloride ions and at least one member independently selected from each of the following groups:

(A) a polysulfide compound of the formula (B) a heterocyclic sulfur compound containing the grouping chi and/or tautomers thereof, where the nitrogen atom and the two carbon atoms are part of a heterocyclic ring; and

(C) a polyether containing at least 5 ether oxygen atoms per molecule;

wherein R is independently a divalent aliphatic or aromatic non-heterocyclic group of 1-10 carbon atoms; R' is hydrogen, a metal cation, a monovalent aliphatic or aromatic group of 1-20 carbon atoms, or the groups -R-SO M or -R--(S)q-RSO M wherein q is an integer 2-5; M is a cation; Z is 0 or 1, R" is hydrogen, a

wherein R' is hydrogen, an alkyl group of l-6 carbon atoms, aryl, alkaryl or aralkyl group.

Sulfide compounds wherein n is an integer 2-4 are preferred. R may be a divalent hydrocarbon group (including such hydrocarbon groups containing inert substituents such as hydroxyl, alkoxy, polyoxyalkylene, halogen, etc.) of 1-10 carbon atoms such as an alkylene group of 1-10 carbon atoms (i.e. CH -CH CH (CH (CH and, in general, (CH wherein p is an integer 1-1-0. R may be a divalent non-heterocyclic group of 1-10 carbon atoms containing 1-3 oxygen, 1-3 sulfur, or 1-3 nitrogen atoms (such as mac @wg @CH..

etc.

In the compound R may be a hydrocarbon radical preferably selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, aryl, alkaryl, including such radicals when inertly substituted. When R is alkyl, it may typically be straight chain alkyl or branched alkyl, including methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-amyl, neopentyl, isoamyl, n-hexyl, isohexyl, heptyls, octyls, decyls, dodecyls, etc. Preferred alkyl includes lower alkyl, i.e. having less than about 8 carbon atoms, i.e. octyls and lower. When R is alkenyl, it may typically be vinyl, allyl, methallyl, buten-l-yl, buten-2-yl, butyn-3-yl, penten-l-yl, hexenyl, heptenyl, octenyl, decenyl, dodecenyl, tetra-decenyl, octadecenyl, etc. When R' is alkynyl, it may typically be ethynyl, propargyl, butynyl, etc. When R is cycloalkyl, it may typically be cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, etc. When R is aralkyl, it may typically be tolyl, xyly, p-ethyphenyl, pnonylphenyl, etc. R may be inertly substituted, e.g. may bear a nonreactive substituent such as alkyl, aryl, cycloalkyl, aralkyl, alkaryl, alkenyl, ether, etc.

Polysulfide compounds of the Formula A may typically be prepared by the reaction of an alkali metal salt of a hydropolysulfide and a sultone according to the reaction:

wherein R, R, M, and n are as previously defined.

Specific illustrative reactions may include the following reactions wherein all unsubstituted carbon atoms are attached to hydrogen atoms:

SSNa OKs-Cg;

O SSCHQCHQCHISOaNQ NazSg 2CH2-CH:

Other preparative reactions which may be used to produce the sulfide compounds employed according to the invention include the direct sulfonation of an organo polysulfide (i.e. direct sulfonation of diphenyl disulfide, ditolyl disulfide, etc.). The polysulfide compounds also may be prepared by the reaction of epichlorohydrin and an alkali metal bisulfite followed by reaction with a polysulfide (such as Na S- R'SNa, wherein R is as previously defined).

Other preparative reactions may include the following:

Typical polysulfide compounds which may be employed according to the invention include the following compounds which are summarized in Table II. In the formula 6 M represents a sodium cation and R, R, and N are as indicated in Table II.

TABLE II [SulIonated polysulfida cooperating brlghteners of the Formula R'(s}.,Rso|Ns Additive R n R A-l.--- 2 (CH2).

A-2..:.' CH; 2 (CH2):

Hi0 a):

A-5. till) 2 (CH2):

(l-0 (CH2)aS0|Na .A-G. NH(CH:)|SO:H 2 (CH2):

A-7. SOsNa 2 SOzNB H;C OH:

A-S- NaOaS (CH2) 2 A-Q. NaOaS E0112):

A-IO. NaOaS CH2) 4 M A-11 NaOaS (CH2) 1 CH2) 2 A-l2-.- Na( (CH2):

A-20. fi

M unzowrezowwmwmxo A AA A Q A-22- NaOaSCHzCIEKOH) CH2 2 OH2CH(OH) CH until all the sulfur is dissolved. Propanesultone (0.12 mole) is added to the stirred solution. Stirring is continued for 30 minutes, during which time a solid precipitates from the solution. Acetone (250 ml.) is then added to give additional solid, which is then filtered, washed with acetone, and dried.

Aliphatic R"(S),,Na compounds are prepared by reaction of R'Q with Na s, where Q is Cl, Br, I, OSO C H OSO C H -CH OSO CH (e.g. compounds A-17, A-l8, A-19). A typical procedure is: To a stirred methanol solution (150 ml.) containing sodium disulfide (0.1 m.) is added dropwise a solution of R'Q (0.1 m.) in methanol (50 ml.) at room temperature. The reaction is slightly exothermic. After the addition is completed the mixture is stirred for 30 minutes. Propane sultone (0.12 m.), which may be dissolved in methanol (50 ml.), is added to the stirred mixture. During the addition of propane sultone a white solid usually precipitates from the solution. The mixture may be heated and stirred at 65 C. for 30 minutes and then cooled. Acetone is added and the solid is filtered and dried.

Compounds of the type of A-9, A-10, A-ll, A-12 are prepared by the reaction of an alkali metal polysulfide (Na S Na S etc.) with a sultone.

Compounds of the type of A-l3, A14, A-lS, A-l6 are prepared according to the reaction sequence:

Instead of sultones, haloalkane sulfonates, including e.g. ClCH- CHOHCH SO Na (prepared by reaction of epichlorohydrin with sodium bisulfite), and in general compounds of the type QSRO M, may be used.

Some polysulfide compounds may also be prepared by the direct sulfonation of an organic polysulfide (e.g. A-7; or A-21 by sulfonation of A-).

Symmetrical disulfides may be prepared by careful oxidation of compounds of the type HRSO Na.

It is sometimes advantageous to prepare aqueous stock solutions of the sulfonated polysulfides containing small amounts of copper sulfate and/ or sulfuric acid. Some precipitation may occur which is eliminated by filtration.

The sulfide compounds of the invention may be present in the copper bath in effective amounts of about 0.001 g./l.-1.0 g./l., preferably 0.005 g./l.0.2 g./l.-0.2 g./l.

The heterocyclic sulfur-containing cooperating additives of this invention contain the grouping:

a heterocyclic sulfur compound containing the grouping -N- -e l l g, l CODZ n and/or tautomers thereof, where the nitrogen atom and the two carbon atoms are part of a heterocyclic ring wherein Z is O or 1; and

' R" is hydrogen, a metal ion or one of the groups and/or tautomers thereof, N-oxides of said compound, isothlourea derivatives, isothioamide derivatives and di- 8 v thiocarbamate derivatives thereof where R; is hydrogen, a metal cation, or the groups NRlfzI RI! wherein R" is hydrogen, an alkyl group of 1-6 carbon atoms, aryl, alkaryl, or aralkyl; X is CR"= or CR and Y is a divalent organogroup of 2 to 16 carbon atoms which forms 1 or more 5 through 7 membered cyclic ring structure or structures with the group (X)-C=N Rt wherein X and R are as hereinbefore defined.

Typical parent substances are: Z-mercapto pyridine, 2- mercapto quinoline, 1- or 4-mercapto isoquinoline; their N-oxides; alkyl, hydroxy, alkoxy, mercapto derivatives of these compounds derived by substitution on the ring carbon atoms; isothioureas, isothioamides and their salts with acids, dithiocarbomates derived by substitution on the bivalent sulfur atom. Among the heteroaliphatic ring compounds thiocaprolactam gives especially good results.

The mercapto compounds may be dissolved before addition to the copper bath in water containing equivalent amounts of alkali hydroxides, in dilute acids or in suitably organic solvents, e.g. alcohols. The isothiourea, isothioamide, dithiocarbamate derivatives are dissolved in water, dilute acids or in suitable solvents such as alcohols, but not in alkali hydroxides as they may decompose therein.

The function of the heterocyclic compounds of group (B) is to produce, in conjunction with the sulfonated polysulfides of group (A) and the polyethers of group (C), leveling and to increase the brightness of the deposits obtained, especially in the low and medium current density range.

The heterocyclic compounds of formula group (B) may be employed in effective amounts, typically 0.1-50 mg./l. and preferably 0.5-20 mg./l. of total aqueous bath composition. Typical heterocyclic group (B) compounds which may be employed according to the invention are given in Table III.

TABLE IIL-HETEROCYCLIC COMPOUNDS (B) B Formula Name 2-merca topyridine Z-pyrb dinethlol) 2-mercapto yrldlne-n-ox do (1- hydroxy-Z-pyridiuethlone).

4- Z-S-pyrldyl isothiouronl 0- um chl ride N-oxlde.

5.-. 2-mercapto+ methylpyrldine.

TABLE III-Continued TABLE III-Continrued B Formula Name B Formula Name 6... CH: 4-methyl-2-S- 17.- 2-mercapto-6- pyrldyl isothlhydroxy ouronium chlopyridine. ride. 5 NH-HCI H SH S--C\ N 18-. fi-hydrgxyiz-sp so- 7'" w; 10 NH-HCI tlililoirllrgnlum 0 0 B. N-oxide. H0 S C N NH: S H 19 2,6-dimereapto N pyridine.

l 0 HS SH 8.-. CH; 4-methyl-2-S- N m1 111 that? 20 'izfit alififiiluiff' Nil-H01 HCLHN NH-HCI chloride.

S C C- S SC\ If NH: HQN N NH: 0 21.-

Thioeaprolaetam 9 2-mercapto-6- (2-thioxohexamethylpyridine. methylene =3 imine).

H1O SH N N H 22-- Z-S-pyrldyl-N- 10 6'methy1-2-S- diethyl dithlo- {)yridyl carbamate.

NH-HCl csoliglillggroruum S CN(CQE5) 8 C N N NH:

Z-merea memethy l pyridine-N- oxide. HzC SH f The heterocyclic cooperating additives of Table III are 0 available commercially. The heterocyclic compounds of 12 Table III with the exception of B-21) are generally prepyrldyl pared from the corresponding halogen compounds, e.g. NH'HCI g flz f gg 2-chloropyridine either by direct reaction with alkali metal mcs0 N-oxlde. hydrosulfide or more frequently just with thiourea join- N NE, ing the respective isothiouronium compounds, which may 1 be converted by alkaline hydrolysis into the corresponding 0 mercapto compounds. B22 was synthesized by reaction 13" zmmapmqumm of 2-chloropyridine with sodium diethyldithiocarbamate. line. Polyethers which may be used according to the process of the invention may have at least 5 ether oxygen atoms V-SH and include polyethers of the formulae:

14 2-S-quinolyl isothiouronium q NH-HCl chloride.

N NH! 15 Z-mereaptoquinoline N- oxide.

R!!! \/-BH N-Z 16-- 2'8 uinol i Z iS gthlOUI ODll-Im n! NH-HCI chloride B N N-oxide.

If NH: R"(0 z )m 0 RIIII(S where R is a monovalent radical such as H, alkyl, alkenyl, alkynyl, alkylaryl, arylalkyl or a heterocyclic radical; and R"" is a mvalent aliphatic, aromatic or heterocyclic radical; m=2 to 100; and

where u and v= to 4, but at least one of u or v must be greater than zero; r+s=6 to 200,000; r=0 when u=0; s=0 when v=0; and T=H, alkyl, benzyl, SO M, H SO M, PO H or C H NHR'.

Suitable polyethers which may be used according to the invention include polyethers set forth in Table IV. The polyether additives may be employed in eflective amounts, typically 0.005-10.0 g./l. and preferably 0.1-1.0 g./l. of total aqueous bath compositions.

TABLE IV.COOPERATING POLYETHE RS Additive C1.... CH CH; CH: CHI

CHr-(ilH-CHz-G-C El C-l-CHr- H-CHI JIH: AYE:

I I (3) m+1l=30 C2..... Formula (3-1 wherein m+n=15. (3-3..." Formula C-1 wherein m+n=10.

04.-...- CH; CH;

cm-b-om-b-Q-o-wmcmm ,11

('JH: (EH; (4)

C-5 Formula (3-4 wherein z=30. C-6..... Formula (3-4 wherein z=40.

CeHnQO (CH2CH20)|H C45"... n-CnHnO (CHzCHaOhsH n-C ;H *1-CHI N-(CHaCHzOhH HzCHzO) 1H z=9-12, y+z= C-10.... H(C:H|O),(C:H|0)g (CIHl0)z(Cl l )I NCHICHIN mcim mcimofl aH| :H4 )v wherein z is about 3 and u is about 3-4 C11.... HO (CaHtO) :H

wherein a: is about 13 C-12..- HO (C:H4O):H

CHaCHfl-CHsCHa-C-CHaCH:

HCH! CHCHB Hg Hg wherein p is about 16.

C21.... CHaCHzh (cimomwimohH wherein z is about 136 (MW. is about 6,000) (3-26-... H0(C2H40)1H wherein z is about 454 (MW. is about 20,000) C-27...- H0(C:H4O),H

wherein 2: is about 4,540 (MW. is about 200,000)

The chloride ion content of the aqueous copper plating bath compositions of the invention may be at least about 0.5 mg./l. and typically from 1.0 mg./l. to 500 mg/l. of aqueous copper plating bath. Good results may be obtained using a chloride ion concentration of from about 3 mg/l. to 100 mg./l. of aqueous copper plating bath composition, and preferably a chloride ion concentration of from 20 mg./l. to mg./l. of aqueous copper plating solution.

Other optional additives used were the following dispersing agents:

measured as poor, fair, good, and very good as follows:

TABLE V Additlves D-1 r H2- 8 :No

NaOaS S 0iNa S DING i i D-3....:: S CINE] (Jim-- I some where n=3 to 6 D-4....::' Oa )n 4 (SOlNB)m n+m=1-2 and preferably =0 when 'm ls D-5...: CnHrwx-i nHm-i wherein each n is an integer 4-12 (preferably 4-8) and each M and M: an alkali metal (preferably Ne or K) or a hydrogen atom.

The following examples are set forth for the purpose of providing those skilled-in-the-art with a better understanding of this invention, and the invention is not to be construed as limited to such examples.

In these examples the aqueous copper plating bath contains unless noted otherwise:

The plating experiments were performed in a Hull Cell containing 250 ml. of this acid copper sulfate bath. The Hull Cell allows one to observe the appearance of the deposit over a wide current density range. In order to judge the degree of leveling the polished brass panels used for these plating tests were scratched with 4/0 emery p01- ishing paper over a horizontal band of about 10 mm. width. The plating temperature used in these experiments was the ambient room temperature (24-30 C.), unless otherwise stated. The total current was 2 amperes and the plating time 10 minutes. Air agitation or mechanical agitation with an oscillating paddle was used as specified in Table VI. The sulfonated polysulfide compounds used are described in Table II, the heterocyclic sulfur compounds in Table III, and the polyethers in Table IV.

For convenience, the results shown in Table VI are classified according to (1) the width of the lustrous current density range (semi-bright to bright) and according to (2) the degree of leveling under the indicated experimental conditions (i.e. a 250 ml. Hull Cell, 2 amperes current, and a ten minute plating time on a metal strip having a band uniformly scratched with 4/0 grit emery paper).

Each property in groups (1) and (2) is independently Property (1) Rating-.- Width of lustrous current density range Poor Less than one half of Poor No visual change in length of test panel. original roughness of scratched band. Fair More than one half and Falr...-- Noticeable decrease in less than two thirds roughness, but of length of test panel. scratches still visible. Good-.... More than two thirds Good. Roughness decreased but less than entire and portions of length of test panel. scrailzches completely eve Very Entire length of test Very Scratches on the portion good. panel ISIUSUOHS. good. of the panel having a current density greater than 2.5 asd. are practically invisible.

The combination of the panel ratings given with re spect to width of lustrous current density range and degree of leveling determine the final classification set forth in the Results column of Table VI according to the following: Result Definition Excellent Very good leveling and very good bright current density range. Very good Very good leveling and good bright current density range. Good Good to very good leveling and good to very good semibright current density range or: good leveling and good to very good bright current density range. Poor Poor leveling and/or poor lustrous current density range. Fair All intermediate panels not otherwise classified.

TABLE VI TABLE VI-Continued Example Amounts, Type of Example Amounts, Type of number Additive g./l. agitation Results number Additive g./l. agitation Results 1 {A-l Air Poor. A-11 0.02 Air. Good.

--------- -1 Do. 40..-... 0-10 1.0 Air... Do.

A-l Very good. 13-11 0.004 Air- Do. 2 O-l Do. A-li 0.02 Air.-. Good.

B-3 Do. 41 0-10 1 0 Air-.. Do. A-1 0.02 Excellent. 13-12 0.003 Air--- D0. 3 C-l Do. 42 A-12 0.02 Air Poor.

B-11 Do. (3-18 1.0 Air.-. Do. A-l Air Excellent. A-12 0.02 Air... Good. 4 C-l Air Do. 43 C-18 1.0 Air... Do. B-12 0.003 Air Do. 3-2 0004 Air--- Do. 5 11-1 0.02 Mechanical" Poor. A-12 0. 02 Air.. Good.

(3-7 1.0 .--do......- 0- 44 C-18 1.0 Air.. Do. A-l 0.02 MechanicaL. Excellent. B-18 0.008 Air.. Do. 6 C-7 1.0 do Do. 45 A- 002,004 Air.. Poor.

13-5 0.002 .....do Do. C-15 1.0 Air D0. 7 {A-l 0.02 MechanicaL. Poor. 15 A-15 0.04 Air Very good.

(3-8 1.0 -.do....... Do. 40 0-15 1.0 Air D0. A-l 0.02 MechenlcaL. Excell nt. B-l 0.002 Air Do. 8 (3-8 1.0 o. Do. A-15 0.02 Air Very good.

B-io 0.002 -...do.. D0. 47 0-15 1.0 Air Do. 9 A-2 0.02 Poor. B-3 0.004 Air Do. (3-13 1.0 Do. A-15 0.02 Air.. Good.

A-2 0.02 Veryg od. 48 (3-15 1.0 Air.. Do. 10 013 1.0 Do. 13-13 0.002 Air-- Do 13-21 0.003 Do. 49 A-17 0. 02 Air.. Poor. n {A-G 0.02 Poor. C-21 1.0 Air.. Do. 0-1 1.0 Do. A-17 0.02 Air.- Poor.

A-6 0.002 Good. 50 C-21 1.0 Air.. Do. 12 0-1 1.0 Do. D-l 0.4 Air.. Do.

B-i 0.003 Do. A-17 0. 02 Air-. Good but pitted. A-0 0.02 Good. 51 0-21 1.0 Air-. Do. 13 (3-1 1.0 Do. B-lB 0.000 Alia. Do.

B-3 0.004 Do. A-l7 0. 02 Air-. Very good. A4! 0.02 Very good. 52 C-21 1.0 Air.. Do. 14 0-1 1.0 Do. B-is 0.000 Air.. Do. B-l3 0.002 Do. D-l 0.4 Air Do. 15 {A-a 0.015 Poor. 53 {A-18 0.02 MechanleaL. Poor.

"""" C-13 0.25 Do. C-6 1.0 ..do....... Do.

A-9 0.015 Very good A-18 0.02 Meeham'caL. Good. 16 C-13 0.25 Do. 54 0-0 1.0 --.--do Do.

2 5 v 0 i 0 0 9 00 e 17 c-13 0.25 n ii. 55 "{0-20 1 0 13-2 0.003 Do. A-ls 0.02 A-9 0.015 Very good- 56 C-26 1 0 1s c-13 0.25 Air Do. B-19 0.003

ii-5 0.003 Air Do. 19 232 9. 1 1 321112: 150. Dispersing agents 20 :3 15131: ig gf" Addition of a dispersing agent such as D-l to the B-1 0.003 Air Do A B C corn on om i es im 1' ve the ratin b A-9 0.015 Air Very good bmatl s p O s g y 21 M Mr increasing the rate of leveling and/or the lustrous current -3 0004 r density range (Examples 51 and 52 A-9 22 {C-22 0 i 1 iii----. Emelggflt In other cases, addition of D-l does not appreciably (W03 change the rating but increases the degree of brightness A-9 0.015 Air Good. 23 M pm or eliminates microroughness. (Examples 23 and 24.)

13-13 0.002 Air Do. 4 A-9 0. 015 Air Good (less micro- Fluoborate bath 24 C-22 1.0 Air roughness). 1 3-1 3 0.80: fir go- For a fluoborate bath of the preferred composition indi- 51: cated in Table I, the additives of Example 35 gave equally 25 .0 Air D excellent results. Use of the fluoborate bath allows to in- B-14 0.020 Air Do. @015 Excellent crease plating speeds by 50 to 100%. 6 Air Although this invention has been illustrated by refer- B-le 0.002 Air Do. h M15 Excellent, ence to specific embodiments, modifications thereof whic 27 1 are clearly within the scope of the invention will be appar- B-is 0.004 Do. 0, M15 Good, ent to those skilled-in-the-art. 28 gig 0 2 33- What is claimed is:

0:015 Good. 1. A process for electrodepositing bright, strongly 29 gig 5- 3 33- leveled, ductile copper from an aqueous acidic copper 01015 Excelleiit. plating bath containing chloride ions and at least one 30 0 5 g 38- member independently selected from each of the follow- 31 {8-3 01 )13 Excellent. s groups:

3-32 002 Do. (A) 0.001 g./l. to 1.0 g./l. of a polysulfide compound of 32 I &2 i' the formula 0.015 Excellent. 33 0-25 0.25 Do. EH8)" R XI; 88% (B) 0.1 mg./l. to 50 mg./1. of a heterocyclic sulfur com- 34 0-25 1.0 Do. pound containing the grouping l 35 0. 91(5) Excellent. 0-

12-51 0.004 G do. 32 4;

13-13 0.002 Do. 37 {5'3 M15 and/or tautomers thereof N-oxides of said compound, A:9 31% ;5 isothiourea derivatives, isothioamide derivatives and di- 38 5:? 0 8 3 thiocarbamate derivatives thereof; and 39 A-ii .00 POOL (C) 0.005 to 10 g./]. of a polymer containing at least 5 040 1.0 Do- 7 ether Oxygen atoms per mole ule;

wherein R is hydrogen, an alkyl group of 1-6 carbon atoms, aryl, alkaryl or aralkyl group; X is CR": or CR and Y is a divalent organo group of 2 to 16 carbon atoms which forms 1 or more 5 through 7 membered cyclic ring structure or structures with the group wherein X and R" are as hereinbeforedefined.

2. The process of claim 1 wherein said heterocyclic sulfur compound is Z-mercaptopyridine (Z-pyridinethiol).

3. The process of claim 1 wherein said heterocyclic sulfur compound is 2-S-pyridyl isothiouronium chloride.

4. The process of claim 1 wherein said heterocyclic sulfur compound is Z-mercaptopyridine-n-oxide (l-hydroxy-2-pyridinethione).

5. The process of claim 1 wherein said heterocyclic sulfur compound is 2-S-p'yridyl isothiouronium chloride N-oxide.

6. The process of claim 1 wherein said heterocyclic sulfur compound is Z-mercapto-4-methylpyridine.

.7. The process of claim 1 wherein said heterocyclic sulfur compound is 4-methyl-2-S-pyridyl isothiouronium chloride.

8. The process of claim 1 wherein said heterocyclic sulfur compound is 2-mercapto-4-methylpyridine-N-oxide.

9. The process of claim 1 wherein said heterocyclic sulfur compound is 4-methyl-2-S-pyridyl isothiouronium chloride N-oxide.

10. The process of claim 1 wherein said heterocyclic sulfur compound is 2-mercapto-6-methylpyridine.

11. The process of claim 1 wherein said heterocyclic sulfur compound is 6-methyl-2-S-pyridyl isothiouronium chloride.

12. The process of claim 1 wherein said heterocyclic sulfur compound is 2-mercapto-6-methyl pyridine-N- oxide.

13. The process of claim 1 wherein said heterocyclic sulfur compound is 6-methyl-2-S-pyridyl isothiouronium chloride N-oxide.

14. The process of claim 1 wherein said heterocyclic sulfur compound is 2-mercaptoquinoline.

15. The process of claim 1 wherein said heterocyclic sulfur compound is Z-S-quinolyl isothiouronium chloride.

16. The process of claim 1 wherein said heterocyclic sulfur compound is Z-mercaptoquinoline N-oxide.

17. The process of claim 1 wherein said heterocyclic sulfur compound is 2-S-quinolyl isothiouronium chloride N-oxide.

18. The process of claim 1 wherein said heterocyclic sulfur compound is 2-mercapto-6-hydroxy pyridine.

19. The process of claim 1 wherein said heterocyclic sulfur compound is 6-hydroxy-2-S-pyridyl isothiouronium chloride.

20. The process of claim 1 wherein said heterocyclic sulfur compound is 2,6-dimercapto pyridine.

21. The process of claim 1 wherein said heterocyclic sulfur compound is 2,6-SS-pyridyl bis-isothiouronium chloride.

22. The process of'claim 1 wherein said heterocyclic sulfur compound is thiocaprolactam (2-thioxohexameth yleneimine).

23. The process of claim 1 wherein said heterocyclic sulfur compound is Z-S-pyridyl-N-diethyl dithiocarbamate.

24. An aqueous acidic copper electroplating bath containing chloride ions and at least one member independently selected from each of the following groups: (A) 0.001 g./l. to 1.0 g./l. of a polysulfide compound of the formula R(S) -RS0 M; (B) -0.1 mg./l. to 50 mg./l. of a heterocyclic sulfur compound containing the grouping (X)C s R" and/ or tautomers thereof, N-oxides of said compound, isothiourea derivatives, isothiomide derivatives and dithiocarbamate derivatives thereof; and

'(C) 0.005 to 10 g./l. of a polyether containing at least 5 ether oxygen atoms per molecule;

wherein R is independently a divalent aliphatic or aromatic non-heterocyclic group of 11() carbon atoms, n is an integer 24; R is hydrogen, a metal cation, a monovalent aliphatic or aromatic group of 1-20 carbon atoms, or the groups R-SO M or -R-(S)q-RSO M wherein q is an integer 2-5; M is a cation; R is hydrogen, a metal ion or one of the groups:

wherein R is hydrogen, an alkyl group of 1- 6 carbon atoms, aryl, alkaryl or aralkyl group; X is CR"=or --CR and Y is a divalent organo group of 2 to 16 carbon atoms which forms 1 or more 5 through 7 membered cyclic ring structure or structures with the group wherein X and R" are as hereinbefore defined.

25. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2-mercaptopyridine (2-pyridinethiol).

26. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is Z-S-pyridyl isothiouronium chloride.

27. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2 mercaptopyridine n oxide (1-hydroxy-2-pyridinethione).

28. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is Z-S-pyridyl isothiouronium chloride N-oxide.

29. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2-mercapto-4-methylpyridine. v

30. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 4-methyl-2-S-pyridyl isothiouronium chloride.

31. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2-mercapto-4-methylpyridine-N-oxide.

32. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 4-methyl-2-S-pyridyl isothiouronium chloride N-oxide.

33. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2-mercapto-6 methylpyridine.

34. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 6-methyl-2-S-pyridyl isothiouronium chloride.

35. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2-mercapto-6-methyl pyridine-N-oxide.

36. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 6-methyl-2-SPpyridyl isothiouronium chloride N-oxide.

37. An aqueous acidic copper plating 'bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2-mercaptoquinoline.

38. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2-S-quinoly1 isothiouronium chloride.

39. An aqueous acidic copper plating bath as claimed in claim 24. wherein the heterocyclic sulfur compound is Z-mercaptoquinoline N-oxide.

40. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is Z-S-quinolyl isothiouronium chloride N-oxide.

41. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2-mercapto-6-hydroxy pyridine.

42. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 6-hydroxy-2-S-pyridyl isothiouronium chloride.

43. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2,6-dimercapto pyridine.

44. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocycic sulfur compound is 2,6-SS-pyridyl bis-isothiouronium chloride.

45. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is thiocaprolactam (2-thioxohexamethyleneimine).

46. An aqueous acidic copper plating bath as claimed in claim 24 wherein the heterocyclic sulfur compound is 2-S-pyridy1-N-diethyl dithiocarbamate.

References Cited UNITED STATES PATENTS 3,542,655 11/1970 Kardos et a1 204-52 R 3,682,788 8/1972 Kardos et al 20452 R GERALD L. KAPLAN, Primary Examiner 

